1. Field of the Invention
The present invention relates to a heat pump system operable with the use of a non-azeotropic mixed coolant and capable of changing the composition of the non-azeotropic mixed coolant while storing a high boiling point coolant separated from the non-azeotropic mixed coolant.
2. Description of the Prior Art
Hitherto, the heat pump system capable of changing the composition of the non-azeotropic mixed coolant while storing a high boiling point coolant separated from the non-azeotropic mixed coolant has been available in the form as shown in FIG. 6 of the accompanying drawing. Referring to FIG. 6, the system comprises a main fluid circuit including a compressor 1, a condenser 2, a throttling device 3 and an evaporator 4 all fluid-connected as shown. Reference numeral 5 represents a fractionating separator having an upper end fluid-connected with the outlet of the condenser 2 through a piping 6 and also with the inlet of the evaporator 4 through a pressure reducer 7. A reservoir 8 is disposed beneath a lower end of the fractionating separator 5, the bottom of which is fluid-connected with the pressure reducer 7 through a shut-off valve 9. This reservoir 8 has a heater 10 built therein.
The prior art heat pump system of the construction described with reference to FIG. 6 is selectively operable in one of the two modes; the non-fractionating mode in which the system operates with the mixed coolant filled therein without altering the composition thereof, and the fractionating mode in which, while a high boiling point coolant is stored, the system operates with the composition rich of a low boiling point coolant. Hereinafter, the method practiced by the prior art system for changing the composition of the non-azeotropic mixed coolant filled therein will be described.
During the non-fractionating mode, and when the heater 10 is turned off, the reservoir 8 merely stores an excessive coolant and, during the closure of the shut-off valve 9, it stores the coolant, but during the opening of the shut-off valve 9, the coolant is in part stored and in part passed to the evaporator 4 through the pressure reducer 7. Accordingly, the main fluid circuit operates with the mixed coolant whose composition is rich of a high boiling point coolant filled in the system.
On the other hand, during the fractionating mode, and when the shut-off valve 9 is closed and the heater 10 is turned on, a low boiling point coolant contained in the coolant stored in the reservoir 8 is evaporated to pass upwardly through the interior of the fractionating separator 5. At this time, a liquid coolant is supplied from the exhibit of the condenser 2 by way of the piping 6 to the fractionating separator 5 in which fractionating takes place by the effect of a gas-liquid contact so that the gaseous medium which ascends becomes rich of the low boiling point coolant while the gaseous medium which descends becomes rich of the high boiling point cooling, allowing the high boiling point coolant to be stored in the reservoir 8 in the form of a condensed liquid. The ascending gaseous medium rich of the low boiling point coolant flows into the evaporator 4 through the pressure reducer 7 and, therefore, the main fluid circuit operates with the composition rich of the low boiling point coolant.
The heat pump system of such a composition-variable type is applied in, for example, a hot-water supply system and is usually operated with the filled composition rich of the high boiling point coolant so that, during the use thereof, a hot water can be available. Where the hot water is stored in a time as short as possible, the heat pump system can be operated with the composition rich of the low boiling point coolant having a high heating capability.
However, the prior art heat pump system of the above described type has a problem in that, since the fractionating is carried out by the use of the heater, the energy conversion efficiency tends to be lowered at the time the composition is changed. In other words, the amount of heat produced by the heater is merely utilized for the production of the gaseous medium for the fractionating and, for example, no utilization by the heat recovery to the site of use where hot water is actually utilized is effected.